Production of improved effects on cellulosic fabrics



Patented May 3 1 UNITED TAT PATENT. oFF-icsrnoDUo'rIoN or IMPROVED EFFECTS 0N OELLULOSIC memos No Drawing. Application July 23, 1936, Serial No. 92,223. In Great Britain January 16, 1935 I t 5 Claims; .This invention relates to the production of imcomposed wholly or partly of yarns consisting of iroved effects on woven, knitted or other .fabrics r comprising filaments ofmaterials having a fibrous cellulosic origin, such for example as un- 'mercerized and mercerized cotton and linen and/or of regenerated cellulose such for example as viscose-rayon and cupramnionium rayon. The

particular nature of the eifects concerned'is that involving operations (hereinafter called mechan-' ical operations or mechanical treatments) which alter the surface conformation of the material, such asembossing, schreinering, glazing, beetling and the like.

Hitherto the effects produced on the aforementioned fabrics have had the defect of not being resistant to washing, launderingyhot damp pressing and like operations to which the fabrics maybe subjected. The object of the present invention is to overcome this defect.

According to the inventionthe'fabric is, treated,

I for example wetted, damped or impregnated with an aqueous solution of formaldehyde and with an acid reacting catalyst as hereinafter defined After such treatment of the fabric any excess liquor is removed and then, before or after drying,

"the particular mechanical operation concerned temperature is, for example, C. to C. Thei' dried fabric anay be conditioned either naturally why any known means in order to restore the natural moisture content prior to the mechanical treatment. .It may be possible-to dispense altogether with drying in some'c'ases, more partie- 7 ularly in the case of heavy cloth. It isiniportant that the mechanical operation concerned shall take place before the completereaction takes place.

After the mechanical operation the fabric is' subjected to a heat treatment at a temperature of the order or .110 C. and above in' order tol cause the, complete reaction .to take place. The preferred range of temperature is "C. to 0., the time of heating required to bring about the complete reaction being longer atthe lower. temperatures than at the higher temperatures, :but caremust be taken not to use such a j high temperature that-the cellulose is decom- ..',posed. 7

It .will thenbe found that the embossed, glazed,-

beetled or other mechanically produced eifect on thefabric will be highly resistant to washing, laundering, hot damp pressing etc. and this is obtained without substantially changing the feel of the fabric. 1

The precise'nature of the reaction of the cellu- ,lose is not at present known, but there is a definite reaction as is evidenced by the fact that the cellulose becomes insoluble in the customary copper-ammonia solution. Continued heating, after this change has occurred, would not appear to produce any further reaction until actual decomposition'of the cellulose takes-place, due to the effect of the acid or to charring. Accordingly, by the term (complete reaction? is to' be understood that the cellulose has reacted to the point where it is no longer soluble in the customary copper-ammonia solution.

The treatedmaterial usually retains an odor of formaldehyde and for removing traces of the latter it may be necessary to subject the treated material to a washing operatiomfor example, "with ammonia and/or soap solution.

The heat treatment may be accomplished in a heated-chamber or by passing the fabric over heated cylinders or rollers or by a passage through a hot flue or chamber. There 'may be. incorporated in the wetting, damping or-impregnating liquid other materials ordinarily used as fillers, such as starch, dextrine glue, china clay, etc.

Catalysts employed in the present process are suchsubstances more not volatile under the tions of the'treatment, e. g. organic acids such r as oxalic and tartaric acids, acid salts of organic acids such as sodium acid tartrate, and potassiatein water solution to, give an acid reaction,

such asammonium sulphocyanide. The catalysts need only be used in the proportion'of .1% to 1 of the impregnating "liquid.

specified, dried, if necessary conditioned, and woven to a fabric which is then subjected to mechanical treatment as abovefdescribed, followed by the final heat treatment. In this case care may have'to be taken not to delay the weaving According to a modified form of the present invention a yarn can be treated with the "reagents,

of the treated yarn in order that the effect shall not be lost.

The following examples illustrate the inven- Example 1 A viscose fabric to be treated is impregnated with a 10% solution of formaldehyde in water containing 0.6% of oxalic acid and after thorough wringing the solvent is removed at a temperature of about C. The dried fabric is then embossed and afterwards heated to a sufficiently high temperature, 130 C. to 140 C., until the reaction is completed.

Example 2 Example 3 A cotton fabric is impregnated on the pad with an aqueous solution of formaldehyde containing 6% formaldehyde and 0.6% ammonium sulphocyanide. After drying at 50 C. and conditioning so that the fabric contains 15% of moisture, the fabric is subjected to mechanical treatment, e. g. glazing, beetling or embossing. A heat treatment follows by means of hot cylinders so that the fabric is heated to 140 C. for 7 minutes. A passage through a dilute ammonia solution is given, followed by drying to complete the operations.

What we claim is:-

1. Process for producing improved effects on fabrics composed wholly or partly of cellulosic materials, comprising the steps of causing the fabric to contain formaldehyde and an acid reacting catalyst, the amount of the acid reacting catalyst being small as compared with the amount of formaldehyde, mechanically treating the fabric by compression to alter the surface conformation of -the material, and then heating to a temperature of the order of C. and above.

2'. Process for producing improved effects on fabrics composed wholly or partly of cellulosic materials, comprising the steps of impregnating the fabric with an aqueous solution of formaldehyde containing an acid reacting catalyst, the amount of the acid reacting catalyst being small as compared with the amount of formaldehyde, mechanically treating the fabric by compression to alter the surface conformation of the material, and then heating to a temperature of the order of 110 C. and above.

3. Process as claimed in claim 2, in which the fabric after impregnation is freed from excess liquid and dried before the mechanical treatment.

4. Process for producing improved effects on fabrics composed wholly or partly of cellulosic materials, comprising the steps of impregnating" the fabric with an aqueous solution of formaldehyde containing an acid reacting catalyst, the

amount of the acid reacting catalyst being small as compared with the amount of formaldehyde, removing excess liquor; drying, mechanically treating the fabric by compression to alter the surface combination of the material, and then heating to a temperature of -160 C.

5. The process for producing improved effects on fabrics composed wholly or partly of cellulosic materials, comprising the steps of mechanically treating such fabric carryingformaldehyde and an acid reacting catalyst, the amount of the acid reacting catalyst being small as compared with the amount of formaldehyde, to alter the surface conformation of the material by compression, and then heating to a temperature of the order of 110 C. and above,

HAROLD HENRY BOWEN. VICTOR HOFFMANN MAJERUS. 

